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United States Patent | 5,237,192 |
Shimura | August 17, 1993 |
A method of producing a MESFET, and the MESFET formed by the method, which includes forming a refractory metal gate structure on an active layer formed in or on a semiconductor substrate. Source and drain regions are formed adjacent the gate structure. An insulating film is deposited over the partly formed structure to form a film portion on the semiconductor substrate which is separated from further film portions formed over the source and drain regions. A flattening resist is deposited over the insulating film and etched to expose only the film portion on the gate structure, while the gate structure itself and the resist protects the film portions on the source and drain regions. The film portion over the gate structure can thus be removed without damage to the gate structure or the remainder of the insulting film. A low resistance metal is patterned and deposited over the gate structure and overlies, in part, at least a part of the insulating film which remains over the source and drain regions. The gate structure can be single metal layer or can be a T-shaped structure formed of two refractory metal layers. The process produces with increased yield and more consistent properties in that the danger of attacking the refractory metal gate structure during operations succeeding its formation is significantly reduced.
Inventors: | Shimura; Teruyuki (Itami, JP) |
Assignee: | Mitsubishi Denki Kabushiki Kaisha (Tokyo, JP) |
Appl. No.: | 800749 |
Filed: | November 29, 1991 |
Dec 12, 1988[JP] | 63-258007 |
Current U.S. Class: | 257/280; 257/282; 257/283; 257/284; 257/757; 257/E21.454; 257/E29.127 |
Intern'l Class: | H01L 029/80; H01L 023/48 |
Field of Search: | 357/22 I,22,68,71,71 S,71 T 437/41,184 257/280,281,282,283,284,472,757,764,770 |
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Foreign Patent Documents | |||
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"A New Refractory Self-Aligned Gate Technology for GaAs Microwave Power FET's and MMIC's", by Geissberger et al., IEEE Transactions on Electron Devices, vol. 35, No. 5, May 1988, pp. 615-622. |